Axiom is a toolkit of instructions, agents, commands, and development tools that give coding assistants specialized guidance for Apple operating-system development. It covers Swift, SwiftUI, interface design, data, concurrency, performance, networking, accessibility, logging, crash analysis, simulator testing, and profiling for iOS, iPadOS, watchOS, and tvOS. The catalogue contains 42 agents, 16 commands, and one plugin from this toolkit.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add CharlesWiltgen/Axiom --skill axiom-concurrencygit clone --depth 1 https://github.com/CharlesWiltgen/AxiomWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/charleswiltgen/axiom/axiom-concurrency)<a href="https://agentmods.dev/skills/charleswiltgen/axiom/axiom-concurrency"><img src="https://agentmods.dev/badge/skills/charleswiltgen/axiom/axiom-concurrency/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/charleswiltgen/axiom/axiom-concurrency"><img src="https://agentmods.dev/badge/skills/charleswiltgen/axiom/axiom-concurrency.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00049 | $0.02893 |
| Opus 5.5 | $0.00020 | $0.01157 |
| Sonnet 5.5 | $0.00010 | $0.00579 |
| Haiku 4.5 | $0.00005 | $0.00289 |
Grade A, and why
axiom-concurrency scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 187 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Concurrency
You MUST use this skill for ANY concurrency, async/await, threading, or Swift 6 concurrency work.
Bundled tools on Claude Code: if command -v <tool> finds nothing (hooks off or --bare), use <plugin-root>/tools/<tool> in place of the bare name; <plugin-root> is two levels above this skill's Base directory for this skill: path.
Can't launch Axiom agents? Where this router sends you to an agent, follow its procedure inline. Over MCP,
axiom_get_agentreturns it; elsewhere, read its file below, which needs only file search and read.Available here:
skills/concurrency-auditor.md.For any other agent, over MCP
axiom_get_agentreturns it too; run its xclog, xcsym and xcprof steps with theaxiom_xclog_*,axiom_xcsym_*andaxiom_xcprof_*tools. Elsewhere, search Axiom's skills forskills/<agent>.md; if there is none, do that work yourself with this suite's skills, using any Axiom tool on yourPATH.
Quick Reference
| Symptom / Task | Reference |
|---|---|
| async/await patterns, @MainActor, actors | See skills/swift-concurrency.md |
| Data race errors, Sendable conformance | See skills/swift-concurrency.md |
| Swift 6 migration, @concurrent attribute | See skills/swift-concurrency.md |
| Actor definition, reentrancy, global actors | See skills/swift-concurrency-ref.md |
| Task/TaskGroup/cancellation API | See skills/swift-concurrency-ref.md |
| AsyncStream, continuations | See skills/swift-concurrency-ref.md |
| DispatchQueue → actor migration | See skills/swift-concurrency-ref.md |
| Mutex (iOS 18+), OSAllocatedUnfairLock | See skills/synchronization.md |
| Atomic types, lock vs actor decision | See skills/synchronization.md |
| MainActor.assumeIsolated | See skills/assume-isolated.md |
| @preconcurrency protocol conformances | See skills/assume-isolated.md |
| Legacy delegate callbacks | See skills/assume-isolated.md |
Warning-free build crashes with _dispatch_assert_queue_fail |
See skills/isolation-inheritance-diag.md |
Crash signature _swift_task_checkIsolatedSwift |
See skills/isolation-inheritance-diag.md |
Core Data context.perform runtime crash inside @MainActor class |
See skills/isolation-inheritance-diag.md |
Combine .map/.sink crash from receive(on:) placement |
See skills/isolation-inheritance-diag.md |
| Delegate method crash from isolation inheritance (CLLocationManager, NSDocument, AVAudioPlayerDelegate, WKNavigationDelegate, PHPhotoLibraryChangeObserver) | See skills/isolation-inheritance-diag.md |
PhotoKit performChanges block traps on PhotoKit's queue |
See skills/isolation-inheritance-diag.md |
| Actor reentrancy / stale state across await | See skills/isolation-inheritance-diag.md |
| Swift Concurrency Instruments template | See skills/concurrency-profiling.md |
| Actor contention diagnosis | See skills/concurrency-profiling.md |
| Thread pool exhaustion | See skills/concurrency-profiling.md |
What ships with it
7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 11d ago Changed 9c4d6636b0d3
- 13d ago Changed · +2 lines 33f4bc5180cf
- 1mo ago Changed 0785b4892672
- 1mo ago Changed · +6 tokens per session dc694b1a6b0f
- 1mo ago First seen · 185 lines · 43 tokens per session scan A 2d2491ca9326
axiom-concurrency is a skill published in the GitHub repository CharlesWiltgen/Axiom (1,231 stars, last pushed yesterday), licensed MIT. It adds 49 tokens to every session and 2,893 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-06.
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